Brake system is one of the most important and essential parts of a motor vehicle which is to be maintained for the safety of passengers inside the vehicle and for the safety of others on the road. In general the brake system comprises of a brake pedal, a power brake booster, a master cylinder, hydraulic lines, wheel cylinder and disc brakes and/or drum brakes. A vacuum pump is present in the brake system to provide the vacuum power. The vacuum pump is activated continuously when the engine starts and supplies vacuum to the break booster. Power brake booster provides the pneumatic boosting to enhance the force from the brake pedal by utilizing the pressure difference between the vacuum chamber and the working chamber. The force thus generated pushes the disc brakes and/or drum brakes to generate an adequate braking force for the vehicles.
One of the main advantages of using the vacuum brake system in a motor vehicle is to provide the required force at the brakes of a motor vehicle. When a driver presses the brake pedal they will feel assistance from the braking system without which the brake pedal would feel very hard. The pump provides higher amount of vacuum whenever it is required. Normally the pressure comes from negative to atmospheric in the brake booster when heavy braking is applied, which further causes a decrease in amplification during braking. This condition of high pressure in the brake booster during the condition of heavy braking is removed by using an auxiliary vacuum pump which can maintain, or even increase the amplification during a heavy braking phase.
During operation of the vacuum pump, oil is drawn from the oil reservoir and fed in to the vacuum pump. This oil feed creates a sealing between the moving part and the stationary part and helps to suck the air from the booster. When the vacuum pump is in working condition the inlet oil enters from the engine oil gallery to the pump through the oil orifice channel and create lubrication and sealing. At the same time from the pump inside pressure chamber the oil pressurized and it goes out to the reservoir through the reed valves. The oil flow rate from the oil reservoir is controlled by the oil pump. After reaching the booster in full vacuum the pump still rotates and the oil flow also continues in to the pump. The vane pushes the oil continuously from the pressure chamber to go out. This compression of oil creates lot of hydraulic resistance forces up on the vane. Due to this higher hydraulic force on the vane the vane tip load increases and frictional losses occur which reduces the pump life. It also consumes higher mechanical driving power from the driving shaft of the engine to operate the pump. In this case the usual vacuum pump takes extra power from the engine.
In the other hand seal ability of top and bottom face of the vane with housing pocket bottom face and pump cover is very important to avoid leakage between moving and stationary body and to increase vacuum efficiency of the pump. The better is the sealing the lesser the air leakage between the pump chamber and the higher the efficiency of the pump. The present invention also improves the seal ability of the vane and the stationary part inside the pump chamber and increases the vacuum generation efficiency of the pump.
For the reliability of the vacuum braking system more accurate vacuum pressure system is needed.
Therefore, there is a need for a reliable and efficient vacuum pump system which reduces the power losses in the ideal working condition and work for long life.